1. Field of the Invention
This invention relates to a heat exchanger to raise the temperature of a pond liquid for the purpose of evaporating water from the pond liquid and precipitating therefrom salts to be extracted and disposed of or recycled.
2. Description of the Related Art
The present invention has been found to be especially useful in conjunction with a landfill. However, the heat exchanging structure of the present invention could be employed advantageously in environments other than landfills, and actually in conjunction with any environment where it is desirable to remove water from a liquid mixture thereby forming a precipitate of what was previously dissolved or suspended solids and then removing of that concentrated solid. In certain areas of the country where there is no access to ocean discharge, there is an accumulation of water in conjunction with certain endeavors where this water is contaminated and contains salts. Agricultural drainage water, oil and gas well production water, reverse osmosis concentrate, cooling tower blow down, demineralizer regeneration waste, and similar high solids content liquid wastes are generally reintroduced to surface water or ground water without any kind of solids removal treatment. This placing of such liquid wastes on or within the ground is starting to become a not-permitted technique for disposal of such liquid wastes and other ways are being considered to dispose of such liquid wastes. In conjunction with landfills, there is created liquid (leachate) in landfills which is a combination of pollutants from the landfill and rainwater. This leachate is being extracted and placed within a pond located on the surface of the ground. It is intended for the pond to receive heat from the sun and evaporate the water from the pond hopefully leaving a concentrated mixture of dissolved and suspended solids. This concentrated mixture from which all water may have been evaporated is then to be transported to an appropriate land disposal area or a user of the recycled solids.
The problem is that in some environments it is difficult for this water to be evaporated from the pond. Rainwater will accumulate in the pond and frequently more water is accumulated than extracted and the pond can actually overflow. There is a need to increase the evaporation rate of the water within this liquid mixture that is contained within the pond. At the present time, there is no known system that is currently in use that facilitates this evaporation without promoting removal of some of the solid material from the pond. The principal invention is designed to use a low grade heat in order to facilitate this evaporation. The use of the low grade heat to evaporate a liquid mixture within an impoundment is generally defined within U.S. Pat. No. 6,276,872 by the present inventor. The aforementioned patent is directed to the including of a closed heat pipe system within the impoundment for the purpose of raising the liquid temperature of the liquid waste material that is contained within the impoundment. This closed heat pipe system is mounted at the bottom of the impoundment.
The evaporation structure of the aforementioned patent locates the heating system along the bottom of the impoundment. It has been discovered that maximum efficiency for evaporation could be obtained if the heat pipe system could be located directly adjacent the surface of the impoundment rather than at the bottom.
The volume of saline production water from oil and gas wells in New Mexico, Wyoming and Colorado is more than twenty million gallons per day. The volume of saline agricultural drainage water from just the Coachella and Imperial Valleys of California is greater. Some lakes, such as the Salton Sea, have exceedingly high concentration of salts. There is a long sought need to produce an economic way to desalt this water in order to produce a potable quality water and a dry salt cake residue that is suitable to be disposable in a secure landfill or used to extract and recycle minerals. Although it is not necessary that the evaporated water is to be recovered as the water can just be disposed of within the air, it is also considered to be within the scope of this invention that the evaporated water can be condensed and then use as a fresh water resource.
The first basic embodiment of the present invention utilizes a floating heat exchanger which comprises a plurality of elongated pipes mounted between an inlet manifold and an outlet manifold submerged within pond liquid within a pond. The pipes are part of a closed loop system for transporting of heat transfer fluid through the pipes. The pipes are to be placed within the pond liquid. The closed loop system includes a pump and a heater or heat exchanger for moving of the heated heat transfer fluid through the closed loop system to transfer heat to the heat transfer fluid and the floating heat exchanger is to transfer the heat from the heat transfer fluid to the pond. The pond liquid is raised in temperature by heat from the floating heat exchanger to expedite evaporation of water from the pond liquid and the concentration of solids suspended or dissolved in the pond liquid.
A further embodiment of the present invention is where the first basic embodiment is modified by both the inlet manifold and the outlet manifold are located adapted to be exteriorly but adjacent to the pond liquid.
A further embodiment of the present invention is where the first basic embodiment is modified by the pipes being located parallel to each other.
A further embodiment of the present invention is where the first basic embodiment is modified by the pipes being constructed of an adhesion resistant material to deter the accumulation of concentrated solids (scale) thereon.
A further embodiment of the present invention is where the just previous embodiment is modified by the material of the pipes comprising polyethylene.
A second basic embodiment of the present invention comprises utilizing of a pond that contains the pond liquid composed of water and suspended or dissolved solids. The pond liquid has a surface. A floating heat exchanger which comprises a plurality of elongated pipes are placed within the pond liquid and located directly adjacent the surface. One end of the pipes is connected to an inlet manifold, and the opposite end of the pipes is connected to an outlet manifold. Heated heat transfer fluid is pumped through the pipes and the manifolds. The pond liquid is then raised in temperature to expedite evaporation of water from the pond liquid and the concentration of dissolved and suspended solids therein.
A further embodiment of the present invention is where the second basic embodiment is modified by the inlet manifold and outlet manifold being located exteriorly of the pond.
A further embodiment of the present invention is where the second basic embodiment is modified by the pipes being located parallel to each other.
A further embodiment of the present invention is where the second basic embodiment is modified by the pipes being constructed of an adhesion resistant material to deter accumulation of concentrated solids (scale) thereon.
A further embodiment of the present invention is where the just previous embodiment is modified by the material of construction of the pipes comprising a polyethylene.
A third basic embodiment of the present invention comprises a method of evaporating water from a pond that contains a liquid mixture of water and dissolved or suspended solids which comprises the steps of placing a pipe within the pond, flowing a heated heat transfer fluid in a closed loop system through the pipe thereby raising the temperature of the liquid mixture facilitating evaporation of water and concentration of dissolved or suspended solids.
A further embodiment of the present invention is where the third basic embodiment is modified by the pipes being floated upon the evaporating liquid.
A further embodiment of the present invention is where the third basic embodiment is modified by the pipes being constructed of a material that resists the accumulation of concentrated solids or scale thereon which can diminish the flow rate of heat and decrease the overall efficiency of the evaporation system.
A further embodiment of the present invention is where the just previous embodiment is modified by the pipes being constructed of polyethylene.
A further embodiment of the present invention is where the third basic embodiment is modified by constructing the closed loop system to have not only a single pipe but a plurality of pipes interconnected between an inlet manifold and an outlet manifold.
A further embodiment of the present invention is where the third basic embodiment is modified by including a pump and a heater or heat exchanger in the closed loop system.
For a better understanding of the present invention, reference is to be made to the accompanying drawing. It is to be understood that the present invention is not limited to the precise arrangement shown in the drawing.
FIG. 1 is a top plan schematic view of the pond floating heat exchanger of the present invention showing such being mounted in conjunction with a pond;
FIG. 2 is a transverse cross-sectional view taken along line 2xe2x80x942 of FIG. 1 showing in more detail the construction of the floating heat exchanger of the present invention;
FIG. 3 is an enlarged view of a portion of the floating heat exchanger of the present invention taken along line 3xe2x80x943 of FIG. 1;
FIG. 4 is a cross-sectional view through one of the pipes included within the floating heat exchanger and the inlet manifold of the present invention taken along line 4xe2x80x944 of FIG. 3.